The goal of this pilot is to determine the therapeutic efficacy and safety of two formulations of vitamin D analog 25,25,25,27,27,27-Hexafluoro-1 Alpha, 25-dihydroxyvitamin D3 for treatment of plaque psoriasis in adults. This will be accomplished by evaluating the topical application of two petrolatum-based formulations containing F6-1, 25(OH)2D3. The safety and efficacy of these two formulations will be compared with the safety and efficacy of placebo vehicle or Dovonex, a commercially available prescription product which contains a vitamin D analog. A total of up to 45 adults patients with plaque type psoriasis who have lesions over at least 5% of their bodies will be studied. Study subjects will be male and female between the ages of 18-80. The study will be for a total of two months of treatment. One of the test materials will be applied by the patient at the dose of approximately 0.05G to a 25 CM2 lesion. A comparable 25 CM2 psoriasis lesion will receive 0.05 of second test material. The third lesion will receive either 0.05G of petrolatum or Dovonex.